Alain Thurin, 64, a former nurse for the frail L'Oreal heiress, hung himself in the woods near his house, said presiding judge Denis Roucou. A police source said that Thurin was in critical condition.
He is one of 10 members of Bettencourt's entourage accused of taking advantage of the 92-year-old billionaire's growing mental fragility in an explosive legal and political drama that even dragged in former president Nicolas Sarkozy.
The intricate tale began with one of the accused, Francois-Marie Banier, a celebrity photographer who became a close confidant of Bettencourt.
The heiress, worth an estimated USD 39 billion according to Forbes magazine, showered Banier with gifts, such as paintings by Picasso and Matisse, life insurance funds and millions of euros in cash.
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Bettencourt also made him her sole heir, which she would later revoke.
Concerned about his employer's growing fragility, Pascal Bonnefoy in 2009 placed a recorder in her office, whose explosive contents would reveal her weakened mental state and how she was being manipulated by those around her.
A key protagonist among the accused, Patrice de Maistre, who managed Bettencourt's fortune, is heard in the tapes encouraging her to commit tax evasion -- including hiding the purchase of a Seychelles island, according to media accounts of the recordings.
The affair tarnished the latter half of Sarkozy's presidency and when he lost the 2012 election he was placed under formal investigation for illegal campaign financing and taking advantage of Bettencourt.
However the charges against Sarkozy were dropped in October 2013.
But Woerth is still facing five years in prison and de Maistre is charged with money laundering as well as taking advantage of Bettencourt.